Fiber optic cables include one or more optical fibers or other optical waveguides that conduct optical signals, for example carrying voice, data, video, or other information. In a typical cable arrangement, optical fibers are placed in a tubular assembly. A tube may be disposed inside an outer jacket or may form the outer jacket. In either case, the tube typically provides at least some level of protection for the fibers contained therein.
Optical fibers are ordinarily susceptible to damage from water and physical stress. Without an adequate barrier, moisture may gradually migrate into a fiber optic cable and weaken or destroy the cable's optical fibers. Without sufficient physical protection, stress or shock associated with handling the fiber optic cable may transfer to the optical fibers, causing breakage or stress-induced signal attenuation.
One conventional technique for protecting the optical fibers from damage is to fill the cable with a fluid, a gel, a grease, or a thixotropic material that strives to block moisture incursion and to absorb mechanical shock. Such fluids and gels are typically messy and difficult to process, not only in a manufacturing environment but also during field service operations. Field personnel often perform intricate and expensive procedures to clean these conventional materials from the optical fibers to prepare the fiber for splicing, termination, or some other procedure. Any residual gel or fluid can render the splice or termination inoperably defective, for example compromising physical or optical performance.
Another conventional technology for protecting optical fibers entails including a water absorbent chemical within the cable. The chemical absorbs water that inadvertently migrates into the cable, to help prevent the water from interacting with the delicate optical fibers. In one conventional approach, particles of the water absorbent chemical are mixed with the gel discussed above, and the mixture is inserted into the cable. This approach typically suffers from the same drawbacks as using a pure form of a gel; gels and related materials are messy and difficult to process. In another conventional approach, the chemical is applied to the surface of a tape that is inserted in the cable lengthwise. One disadvantage of the tape approach is that the tape typically offers the optical fibers a less than desirable level of cushioning against shock and other forms of physical stress.
Accordingly, to address these representative deficiencies in the art, what is needed is an improved capability for protecting an optical fiber from water damage. Another need exists for protecting an optical fiber from stress or physical damage. Still another need exists for a dry material that can be readily and cleanly disposed in a fiber optic cable to help shield the cable's fibers from physical and/or moisture attack. Yet another need exists for an apparatus that can be inserted in a fiber optic cable to protect the cable's optical fibers, yet that can be removed easily from the cable without leaving a problematic residue or a layer of fluid or gel. One more need exists for a technology that can efficiently carry moisture absorbent material in a dry state into a fiber optic cable. Further need exists for a process to fabricate protective materials and for a process to manufacture fiber optic cables that incorporate such protective materials. A capability addressing one or more of these needs would decrease the cost of making and using fiber optic cabling systems and would promote adoption of optical fibers for communications and other applications.